Effect of Photoperiod and End-of-Day Light Quality on Alkaloids and Phenolic Compounds of Tobacco

Abstract

Tobacco plants (Nicotiana tabacum L.) were grown on long or short photoperiods followed by 5 minutes of red or far red radiation each day. Plants that received 16-hour photoperiods had a significantly higher concentration of total alkaloids and total phenolics than those that received 8-hour photoperiods. Significantly higher total alkaloid content was found in plants that received red rather than far red radiation last each day. Within each photoperiod, plants that received far red had higher concentrations of soluble phenols, particularly of chlorogenic acid. The interactions among these variables upon alkaloid and phenolic contents are discussed.were trimmed to a 2-cm "brush," and leaves at lower stalk positions were removed so that the characteristics of new growth were a function of the assigned treatment. The "conditioned" test plants were then set in aerated nutrient solution (4) and placed under either 8-or 16-hr photoperiods at 25 C under 2000 ft-c of illumination from cool white VHO fluorescent lamps. Roots of test plants were protected from light exposure by placing aluminum foil over the nutrient solution containers.Thirty plants were used for each photoperiod treatment. At the end of their respective photoperiods, each day, half of the test plants were irradiated with 5 min of R, while the other half received 5 min of FR. The intensity of R and FR radiation was adjusted to approximately 360 j,W-2 over the wave length bands of 600 to 700 and 700 to 770 nm, respectively, as described in an earlier report (8).Plants on 16-hr photoperiods were treated for 18 days. Those on 8-hr photoperiods received 20 days of treatment. This 2-day Photocontrol of plant growth and development has been widely studied. Pronounced developmental differences associated with red and far red light, acting through the phytochrome system, occur when such irradiations follow relatively short photoperiods and are followed by long uninterrupted nights (8). Tobacco plants irradiated briefly with FR2 at the end of short days develop long stems with light green leaves relative to those on plants irradiated with R at the end of the day (8). Light of defined spectra was observed to affect levels of phenolic components of many plants (15,16). However, the exact relationships between photoinduced biosynthesis of the compounds and photoinduced growth and development are yet to be established (3). The objective of the research reported herein was to determine whether levels of alkaloids and phenolic compounds of tobacco were influenced by length of photoperiod and/or by manipulation of the phytochrome system with R and FR at the end of the day. MATERIALS AND METHODSTobacco (Nicotiana tabacum L. cv. TI-204-E) seedlings were started and grown for about 6 weeks at 28 C under 14-hr, 1600 ft-c photoperiods from cool white fluorescent lamps. The seedlings were started in vermiculite and subirrigated with halfstrength Hoagland's nutrient solution (4).Photoperiod

Effect of Daylength on Phenol Metabolism in the Leaves of Salvia occidentalis

“…For duckweed Umemoto (13) reported that chlorogenic acid accumulation depended on the daylength: shorter periods than a 12-h photoperiod did not cause accumulation, while the acid was accumulated in proportion to daylengths longer than 12 h. This is similar to the situation in the leaves of S. occidentalis (Fig. 6).…”

“…In 10 experiments with plants which had been in SD (8-h light, 16-h darkness) for 5 days the average increase of absorbancy at 450 nm (see Fig. 5 (4,7,(11)(12)(13)15). The accumulation pattern of the phenolics (Fig.…”

“…The The daylength affects phenol metabolism in the leaves of plants (4,7,(11)(12)(13)15). Attempts have been made to relate this to photoperiodic phenomena, e.g.…”

Alteration of the Alkaloid Profile in Genetically Modified Tobacco Reveals a Role of Methylenetetrahydrofolate Reductase in Nicotine N-Demethylation

“…This is because the plants were grown at different times of the year: the KD plants were grown from April to July, while the OX plants were grown from November to February. Long days are known to favor alkaloid production (Tso et al, 1970). However, the NCRs in vector control lines used in both OX and KD experiments were similar (2.96% and 2.62%) regardless of the growing season, which is in agreement with the NCRs of less than 3.0% that were reported for commercial tobacco lines (Jack et al, 2007).…”

Effects of Transplanting Time on 15-Nitrogen Utilization and Industrial Quality of Flue-Cured Tobacco

“…However, if soil N content is relatively high, additional water increases nicotine concentration as the N uptake under these circumstances exceeds the dilution effect (Biglouei et al, 2010). Moreover, a prolonged photoperiod or short-wavelength sunlight significantly increased nicotine concentration (Tso et al, 1970;Kartusch and Mittendorfer, 1990), but very strong or very weak light intensity led to the highest nicotine concentration in tobacco leaf (Tso, 1990). …”